This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Background: In collaboration with Dr. Don Tucker, this DBP is specifically concerned with improving our ability to reconstruct neuroelectric sources in the brain from EEG measurements. For both research and clinical practice, EEG is a cost-effective tool for understanding brain activity. Although functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) provide high spatial resolution, their temporal resolution is limited and they are based on indirect measures of neurophysiological activity. Advances in EEG technology now include fast, robust, dense (256-channel) sensor arrays, exact sensor position measurement (such as with photogrammetry), and EEG source localization methods that take advantage of carefully regularized linear inverse estimations and precise specification of head tissue geometry from MRI. Rationale: EEG advances have significantly improved the spatial resolution of source estimates and offer the promise of accurate monitoring of cortical activity in both space and time. By itself, high-resolution EEG would be affordable even for small hospitals in remote locations and could be easily managed by technicians in the field. Questions: While the temporal resolution of EEG is limited only by the sampling rate, its spatial resolution is generally assumed to be poor, even in comparison to PET. In fact, the true intrinsic spatial resolution of the human EEG remains unknown because the limits of electrical source reconstruction have not been tested with adequate measurement technology. Design &Methods: Within the broad scope of research activity in the field of neural source imaging, Dr. Tucker and CIBC have chosen a selected subset of potential projects with the goal of maximizing the potential impact of our collaborative work in terms of: (1) Improving near- term translational uses of EEG-based source localization;(2) Moving closer to determining the true resolution possible with EEG;and (3) Improving the capabilities of our other neuroscience collaborators. The algorithms and tools developed in this project will be of immediate use to EGI and Dr. Tucker, and we expect to be able to achieve immediate and broad-based dissemination through their base of more than 400 users of their technology. In addition we believe that our ability to collaboratively begin to assert the true potential resolution of EEG in source imaging could make a very positive contribution to the adoption of this relatively low-cost technology in many research and clinical laboratories.